1. Field of the Invention
The subject matter disclosed generally relates to the field of hard disk drives.
2. Background Information
Hard disk drives contain a plurality of transducers that are magnetically coupled to rotating magnetic disks. The transducers can write and read information onto the rotating disks by magnetizing and sensing the magnetic field of the disks, respectively. The transducers are integrated into heads that are part of a head gimbal assembly (HGA). The HGAs are typically attached to an actuator arm that is pivotally mounted to a base plate of the drive.
Information is typically stored within a plurality of data sectors. The data sectors are located within annular tracks of the disks. The actuator arm has a voice coil that is coupled to a magnet assembly mounted to the base plate. The voice coil and magnet assembly together create a voice coil motor. The voice coil motor can be energized to pivot the actuator arm and move the transducers to different annular tracks of the disks.
Hard disk drives are typically assembled into computer systems such as a portable computer. Movement of the portable computer may induce a rotational acceleration of the disk drive. The rotational acceleration of the disk drive may cause the actuator arm to move about the drive and damage disk drive components. There have been developed a number of latches that secure the actuator arm and prevent undesirable arm movement. The latch is typically engaged when the heads are moved away and unloaded from the disks.
FIG. 1 shows a magnetic latch 1 that can secure an actuator arm 2. The magnetic latch 1 is adjacent to a magnet assembly 3 that is coupled to a voice coil 4 of the arm 2. The actuator arm 2 includes a steel pin 5 that is magnetically attracted to the latch 1. The attractive magnetic force between the pin 5 and latch 1 maintains the position of the actuator arm 2. The actuator arm 2 can only be separated from the latch 1 by providing enough current to the voice coil 4 to create a torque sufficient to overcome the magnetic force. This requires additional power for the hard disk drive, a criteria that is undesirable when used in a portable computer. Additionally, the use of a magnetic latch 1 may require complex actuator speed control that increases the software processing overhead of the drive.
FIGS. 2-4 show an inertia latch 10 that can secure an actuator arm 11 when the disk drive has clockwise rotational acceleration. The inertia latch 10 is normally biased in an open position away from the actuator arm 11. When the disk drive is not writing or accessing information the actuator arm 11 is rotated to park the heads 12 on a ramp 13. The arm 11 also engages a crash stop 14. When the disk drive has a clockwise rotational acceleration the actuator arm 11 moves in a counterclockwise direction. The latch 10 also moves in a counterclockwise direction until a latch hook 15 extends into a notch 16 of the actuator arm 11 as shown in FIG. 3 to secure the arm 11.
As shown in FIG. 4, the latch 10 will move back to the open position when the disk drive is no longer rotationally accelerating. If the hard disk drive has a counterclockwise rotational acceleration, the actuator arm 11 will swing past the latch 10 in a clockwise direction and possibly land on the disks (not shown). This type of latch 10 will not secure the actuator arm 11 for counterclockwise rotational acceleration.
FIGS. 5-7 show a dual lever latch 20 which has a large latch arm 21 that can move a small latch arm 22 into an actuator arm 23. The small latch arm 22 will engage the actuator arm 23 whether the disk drive has clockwise or counterclockwise rotational acceleration. When the disk drive is rotating in a clockwise direction the large latch arm 21 moves in a counterclockwise direction and a first latch pin 24 pulls the small latch arm 22 into the actuator arm 23 as shown in FIG. 6. When the disk drive is rotating in a counterclockwise direction the large latch arm 21 moves in a clockwise direction and a second latch pin 25 pushes the small latch arm 22 into the actuator arm 23 as shown in FIG. 7. The latch 20 will secure the arm 23 regardless of the rotational acceleration direction. This design requires multiple latch components that increases the complexity and cost of mass producing the disk drive.
FIG. 8 shows an impact rebound single lever bi-directional latch 30. The latch 30 has a catch 31 that can engage a corresponding hook portion 32 that extends from an actuator arm 33. When engaged, the hook 32 and catch 31 secure the actuator arm 33 when the disk drive is subjected to a rotational acceleration. The latch 30 includes a tab 34 that is coupled to a magnet (not shown). The tab 34 is attracted to the magnet to pull the latch 30 away from the hook 32 to detach the actuator arm 33.
When the disk drive undergoes a clockwise rotational acceleration the actuator arm 31 and latch 30 will move in a counterclockwise manner. The actuator arm 36 may strike the latch 30 before the hook 32 and catch 31 have engaged. This premature contact may cause the latch to rebound and rotate back in the clockwise direction away from the actuator arm 33. The disk chive includes a crash stop 35 which limits the movement of the latch 30 in the clockwise direction so that the hook 32 will still slide into the catch 31. Having separate latch and stop parts increases the complexity and cost of mass producing the drives. It would be desirable to minimize the number of parts in the latch assembly.
A latch for an actuator arm of a hard disk drive. The latch includes a catch portion, a pusher portion, and a crash stop portion that is located between the catch and pusher portions.